The present invention is related to gas turbine engines, and in particular to actuators for positioning inlet guide vanes and/or rotatable guide vanes.
Gas turbine engines rely on rotating and stationary components to effectively and efficiently control the flow of air through the engine. Rotating components include rotor blades employed in compressor and turbine sections for compressing air and extracting energy from air after combustion. Stationary components include vanes placed in the airflow to aid in directing airflow. By varying the position of the vanes (i.e., rotating them to vary the profile provided to the airflow), airflow characteristics can be optimized for various operating conditions.
The mechanism for providing precise, controlled, and uniform actuation of the vanes is a linear actuator connected to the plurality of vanes located circumferentially around the engine via a series of linkages. The actuator is typically mounted to the exterior of the engine case, and communicates power to the series of linkages via a bell crank or similar mechanical device mounted on a torque box. Installation and alignment of the actuator relative to the bell crank is critical to achieving a desired positioning of the vanes. However, factors such as thermal growth during various flight conditions can adversely affect the alignment of the actuator with the bell crank, which results in errors in between the desired position of inlet guide vanes and the actual position of the inlet guide vanes.